Note 4 - Revenue From Contracts With Customers - Change in Deferred Revenue and Accumulated Deficit (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Deferred revenue			$ 726,061
Accumulated deficit	$ (347,671,102)	$ (336,722,905)	(320,608,968)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Deferred revenue				$ 26,061
Accumulated deficit				$ (319,908,968)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Accounting Standards Update 2014-09 [Member]
Deferred revenue			700,000
Accumulated deficit			$ (700,000)